My Crustle's moveset really sweeps through other people's teams. I give it the item softsand, so it can boost bug type moves. The ability that it has is shell armour because if you want to kill a crustle in 1 hit, you need a critical hit. Ti's moveset is:

Stealth Rocks
Shell smash
x-scissor
Rock wrecker

I usually lead off with stealth rocks or shell smash. If I choose shell smash, the next turn, Ihave to take out the biggest threat because it would 1 shot me. The only problem I have with this moveset is recharge on rock wrecker. I would usually die after I use it.

Stone Edge: STAB.
Earthquake: A Bug With earthquake? It Aint Even that- well I guess it weighs enough.
Swords Dance/Claw Sharpen: YAY!
Stealth Rock/X-Scizzor: Stealth Rock is A Great Move, Even Better now with all these new Bug Types, while X-Scizzor gives more STAB.

His EVs and Nature are best suited for sweeping, and the Salac Berry works really well with Sturdy to fix his low speed and allow him to sweep, as even a 2 Speed Crustle is slow. Shell Smash makes him baws, and Earthquake provides coverage. Stone Edge gives steady power but has low-ish accuracy, while Rock Blast varies in power but can break subs, your choice. X-Scissor is STAB as well and rounds off his excellent coverage. I advise you use him with Rapid Spin support, as the Salace Berry is not guaranteed to work without Sturdy, and hazards can stop that from happening.

I might question the slab on its back, but other than that, the only faults I can find are petty, and are true of every Pokemon. It has weaknesses, it doesn't have all stats over 100, it isn't invincible. This guy is good. In fact, I expect to see him a decent amount. He gives Bug types the good name that they lost from the Pokemon I did a little bit ago.

Ability: Sturdy

EVs: Defense, Sp Def, HP

Stealth Rock: With not many Pokemon able to learn this, this guy becomes very important in that it has this great (I just shivered) move.

Toxic: With the defense this guy has, Toxic is a must.

Sandstorm: This guy has lower (not low, just lower) Sp Def, which Sandstorm takes care of while damaging the foe all the while.

Level Ground/Sand Tomb: Sand Tomb provides more passive damage in a form not affected by Taunt. Level Ground might force some switches, which is great for Stealth Rock, while also doing more damage.

Stone edge(another STAB move, good damage, but you will probably need to use pp up or pp max)

Swords dance(raises attack greatly and since it has such a good defense it can use this 2x without problem)

Rock wrecker(learns this move in lvl 55, massive damage and needs to recharge afterward, with sword dance and STAB it's a one hit KO plus it has good defense again so that turn he recharges don't freak out about it)
This move set is actually pretty good so try it and see if it works, it does for me